Little noticed, days before the holiday break, Boeing petitioned the Federal Aviation Administration for an exemption from key safety standards for the 737 Max 7 — the still-uncertified smallest member of its newest jet family. Since August, earlier models of the Max currently flying passengers in the U.S. have had to limit use of the jet’s engine anti-ice system after Boeing discovered a defect in the system with potentially catastrophic consequences. The flaw could cause the inlet at the front end of the pod surrounding the engine — known as a nacelle — to break and fall off. In an August Ai…